Aleutian disease is an immune complex mediated, parvovirus caused infection of mink. Preclinical incubation periods measured in months or years, extreme hypergammaglobulinemia, viral persistence and death due to glomerulonephritis are additional characteristics. A lymphocyte blastogenesis assay has been utilized to examine the responsiveness of infected mink to viral associated antigens. Mink with advanced disease, regardless of genotype, respond strongly to viral associated antigens as well as to specific protein antigens to which they were sensitized prior to AD infecton. Uninfected mink or mink with nonprogressive infections do not respond to the viral associated antigens. The responding cells are "T" cells indicating that T cell function is not abrogated in infected mink. However, if T cell function is compromised by neonatal thymectomy hypergammaglobulinemia and lesions typical of Aleutian disease do not develop. The relation of T cell function to the massive uncontrolled B cell expansion that occurs in this lymphoproliferative disorder might be defined by studying such cellular phenomenon.